Liquid crystal display (LCD) devices are commonly used flat panel display devices. LCD devices include twisted-nematic (TN) type devices, which may have switching elements such as thin-film transistors (TFTs) for controlling respective pixels, and super-twisted-nematic (STN) type devices. TN and STN devices typically include first and second substrates which have opposing transparent common and pixel electrodes formed thereon, respectively, with a liquid crystal material being sandwiched between the substrates. Unfortunately, TN and STN type LCD devices typically have narrow viewing angles, especially in an up-down direction. Furthermore, since the common electrode and the pixel electrodes are formed on separate substrates, and the two substrates may connected in order to convey signals therebetween, numerous and difficult process steps may be required to produce a display device.
To avoid these problems, in-plane switching (IPS) type LCD devices have been developed. In an IPS LCD device, a plurality of pixel electrodes and common electrodes are formed on the same substrate, as described in European Patent Application No. 93307154.0. The electric field developed between the pixel electrode and the common electrode, which affects the orientation of the molecules of the liquid crystal, is aligned parallel to the substrate, in contrast to the perpendicular electric fields produced by the electrodes of a typical TN or STN LCD device. Unfortunately, however, conventional IPS LCD devices may have an undesirably small aperture ratio, especially when all the electrodes are formed on one substrate.